The foundations of any building within the quarry need to be
carefully investigated, whether they are for the use of the
quarry operator or as part of the after use proposal. In
many cases these issues relate to the quarry
floor were after use development tends to be concentrated,
but also apply to any benches where
buildings are constructed.
The main problems that arise, relate to the failure to construct
adequate foundations and there can be several causes, including:
The consequence of one or more of the above is 'differential
settlement', where the ground beneath part of the building
settles or moves more than that under the remainder.
- The failure to construct on bedrock, for all or part
of the building.
- Building on fill material that is not compacted, or not
- Building across the edge of a former quarry bench because
it is hidden by imported fill material. This results in
only part of the building being supported by bedrock.
- Building on fill material that is affected by water flows
due to inadequate drainage.
- Building on an unstable rock floor caused by underground
mining or solution cavities (a space created by the flow
of water dissolving certain minerals).
will give rise to cracking and distortion within the building.
Other problems that arise relate to services (pipes and cables),
which may be severed by differential settlement. In some cases
the flows in sewers can be reversed.
It is, therefore, essential to have full and adequate historical
excavation plans of any quarry that is being re-developed (see quarry
Buildings can be sited on waste materials within the quarry,
but to avoid significant and damaging settlements these materials
should be of uniform thickness and must be properly compacted
in controlled thin layers. These activities are similar to
those that would be used to construct a highway embankment
and may take many months to complete.